The present invention is directed to a fluid coupling and more particularly to a fluid coupling in which the coupling parts include self sealing, low spill valves for use in pressurized hydraulic systems.
The present invention is an improvement over the type of valve for use in a pressurized hydraulic system disclosed in U.S. Pat. No. 4,540,021.
Couplings with self sealing valves are commonly utilized in fluid circuits to prevent the escape of fluid when the parts are uncoupled. In many applications it is desirable to utilize quick disconnect couplings comprising a male part attached to one end of a fluid conduit and a female coupling member attached to an end of an opposing conduit, such that the opposing male and female parts may be readily disconnected with a short axial movement of the male part from the female part. Typically, the coupling parts are held together by detent balls which are moved radially inwardly such that they engage and retain the male part positioned in the female part.
It is preferable that the spill of the fluid, such as hydraulic fluid be kept as low as possible. An example of a prior art low spill coupling is disclosed in U.S. Pat. No. 5,709,243.
The anti-check fluid coupling according to the present invention, may be used in any number of pressurized systems. Often, the system is a recirculating system and includes at least two of the fluid couplings, according to the present invention.
Fluid couplings are often used with agricultural equipment where the couplings must be readily coupled and uncoupled. In addition, they must be self-sealing and of the "break away" type where the coupling parts automatically separate when the axial tension in the hose line reaches a predetermined force.
One problem, which is known in the art, is that high pressures sometimes exist within the hydraulic circuit. For example, in an agricultural implement hydraulic circuit where the normal operating pressure is 2500 to 3000 psi, it is not unusual for the pressure to reach 5000 psi due to thermal expansion of the system fluid. During a high pressure condition within the implement circuit, the innerlocking of the coupling parts has often been difficult in prior art couplings.
Another problem arises during operation of a high pressure system. It is not unusual for the pressure within the valved coupling to be affected by operational conditions and vibration conditions such that the valves are inadvertently closed. This is normally referred to as checking and is a well known problem in the fluid coupling art.
The object of the present invention is to provide an improved fluid coupling for use in pressurized fluid systems. More specifically, the improved fluid coupling is a low spill coupling which minimizes any fluid discharge from the coupling parts during disengagement.
A further specific object of the present invention is to provide an anti-check fluid coupling to prevent the undesired closing of coupling valves during operation.